Quote:
Originally Posted by Steved
As far as I am aware these tuning boxes (P-tronic, Spider etc) do not alter the boost, they only increase the fuel pressure. That's not to say fuel pressure variations could be logged (max-min), but I was surprised (a few years ago when I had lots of issues with my X5 4.8is) how little information was actually logged. Times may have changed though.
Just to add to this debate, these tuning boxes make a very worthwhile improvement to the driveability of the 35d. Fuel economy improves by around 4mpg, you can now drive in 'D' and get the kind of responsiveness that was previously only available in 'DS'. Overall it feels a more relaxing engine to use and it pulls harder at higher revs before it runs out of momentum.
It would be interesting to compare a proper remap (which alters boost, fueling duration and pressure) with the simpler tuning box. I wonder how the full remap feels by comparison.
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If fuel economy increased, most likely smog/pollution levels did as well. Otherwise BMW would make this standard.
Here in the U.S. we have srict smog standards and regaulr testing is required.